The invention relates to an arrangement for ventilating the passenger compartment of a motor vehicle, particularly a passenger car, having a hinged, or hinged and slidable roof cover of the passenger compartment, having at least one electrically drivable fan in the area of the roof for the supply of outside air into the interior of the passenger compartment, as well as having a solar module integrated into the roof cover for the at least one fan.
This type of an arrangement is known, for example, from the German Patent Document DE-OS 36 43 436 and essentially comprises--at least--one fan having an electric driving motor; a solar module which supplies the driving motor of the fan with electric energy, as well as a supporting element for the solar module and the fan which covers a wall opening of the vehicle and--in addition to its function as the supporting element--also serves another purpose. As examples of such supporting elements, the sliding roof or the sun roof of a vehicle are mentioned, among others. As a preferred embodiment, an arrangement is described in which the fan takes in cooler outside air and blows it into the passenger compartment along the shortest path (see claims 9 to 11, FIGS. 5 and 6). By means of flow guiding elements, the air current may be aimed in a targeted manner at parts which are subjected to particularly high heating when the vehicle is not moving, such as the dashboard and the steering wheel. The fan is designed as a crossflow or transverse-flow fan, the housing of which projects beyond the plane of the roof and has an intake opening facing the rear of the vehicle.
The above-described principle of the direct blowing-in of fresh air is indeed advantageous because the fresh air does not first--as in the case of the taking-in of hot air in the roof area--have to flow through the flow-impairing ducts of the series-produced existing heating system in the area of the engine space. It is also advantageous that particularly hot parts or operating elements, which are subjected to direct sun radiation, may be cooled in a targeted manner and that the heated air can escape in the intended direction through the existing venting ducts from the passenger compartment.
It is also advantageous in the described arrangement that, as a result of the low space requirement of the crossflow or transverse-flow fan as well as its position largely above and in the plane of the roof, the passengers' head room is virtually not restricted.
It is a disadvantage of the described arrangement that the fan housing projects out of the outer contour of the vehicle also during the drive and thus interferes with the aerodynamics and the visual appearance of the vehicle.
However, another significant disadvantage is the poor fluidic efficiency of the selected fan construction (crossflow or transverse-flow fan). According to today's particularly attractive state of the thin-film technique, a solar module can be housed on the relatively small surface of the sun roof or sliding roof which, in the case of a sun radiation of 500 W/m.sup.2 (European conditions) calculated to a perpendicular incidence, results in electrical power of approximately 10 W. An expansion of the solar module to other vehicle body surfaces, as a rule, is not considered useful, one of the reasons being that of retrofitting. Tests on passenger cars have shown that, for the ventilation and cooling to be sufficient when the vehicle is subjected to sun radiation and is not moving, a rate of air flow in the order to 200 m.sup.3 /h is required. This rate of air flow--even if the motor has a maximal design--cannot be achieved by means of the low solar output of 10 W and a fan constructed as a crossflow or transverse-flow blower.
It is known that axial-flow fans operate at a much higher efficiency than, for example, crossflow fans. All solutions using axial-flow fans which have become known for the present purpose, for example, according to the German Patent Documents DE-OS 36 33 495 or DE-OS 35 40 546, have considerable disadvantages which stand in the way of a successful practical application. They limit, for example, the useful solar surface or the passengers' headroom or are unacceptable for aerodynamic and aesthetic reasons.
The solar roofs which are currently offered particularly as a replacement of transparent sun roofs also impair the driving comfort in that they are not transparent in the area of the solar module or are transparent only for a certain wavelength spectrum. Thus, there are solar modules made of amorphous silicon with nonmetallic rear electrodes which are transparent only for red tones.
In view of the disadvantages of the solutions according to the state of the art, it is an object of the invention to provide an arrangement for ventilating the passenger compartment of a motor vehicle which permits an efficient cooling of the passenger compartment heated by sun radiation by utilizing photo-voltaically generated electric energy in which case the surface which is available to the solar module is utilized as well as possible and the fluidic conditions are optimized by a suitable selection of the type and arrangement of fans and which does not have any negative influence on the driving comfort, particularly the passengers' headroom as well as the light conditions in the passenger compartment, nor on the outside appearance of the vehicle.
This object is achieved by means of the combination of characteristics:
wherein the at least one fan is constructed as an axial-flow fan and is arranged in the area below the rear transverse edge of the roof cover with respect to the normal driving direction,
wherein the at least one axial-flow fan is kinematically coupled with the roof cover and with the frame carrying the roof cover in such a manner that, when the roof cover is raised, they are swivelled in a forced manner into an effective position in the opening between the roof cover and the frame, and when the roof cover is lowered, are forced into an ineffective position inside the roof recess formed by the roof cover and its frame, each fan axis extending approximately parallel to the plane of the roof cover in the effective position, and extending approximately perpendicular with respect to it in the ineffective position,
and wherein the solar module covering the surface of the roof cover at least for the most part is constructed as a semiconductor thin-film which has a transparency for the incident sunlight into the interior of the passenger compartment in at least a locally limited manner.
The surface of the roof cover which consists, as a rule, of glass can practically be utilized completely for the housing of the solar module since the fan or fans are linked only to the roof cover, but are not integrated into it. The solar module which is constructed in the semiconductor thin-film technique, in a locally restricted manner, has a transparency for the incident sun light, preferably at many uniformly distributed points (perforation) and thus provides similar lighting conditions as a conventional sun roof which is locally imprinted against excessive sun radiation. The fan or fans are constructed as axial-flow fans--with an optimal efficiency--and are arranged below the rear transverse edge of the roof cover, that is, in the area of the largest roof opening when the cover is raised. Thus, the fans do not project out of the vehicle contour in a disturbing manner in any of the positions.
The optimizing of the flow conditions and of the space requirement is achieved by the fact that the fans can be moved, for example, swivelled between an effective and an ineffective position. For this purpose, they are kinematically connected with the roof cover and its frame and, when the roof cover is swivelled, are forced along with it. The effective position (fan axis is approximately in parallel to the plane of the roof cover) leads to a targeted, low-resistance course of flow; the ineffective position (fan axis is approximately vertical with respect to the plane of the roof cover) permits a low space requirement within the roof recess formed by the frame of the roof cover.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.